Photometry QA

Accessing summary and single-run QA information

Overview of Quality Assurance

In order to assess the overall quality of the SDSS imaging data, each
SDSS imaging run goes through a series of tests to confirm its
overall photometric and astrometric quality. This document describes
these tests in detail, in particular the detailed web pages that are
made summarizing the results. These quality assurance tests have
developed over the course of the survey, and have several goals:

Types of imaging QA

There are two types of quality assurance carried out for each SDSS
imaging run: that produced by each pipeline (astrom, psp, frames, and
nfcalib; see the EDR paper for descriptions of each of these
pipelines, as well as the paper by Pier et al. (2003) for the
astrometry) to diagnose immediate problems with running the pipeline,
and summary quality assurance on the outputs, which is run after the
data are completely reduced and calibrated. The latter final quality
assurance itself comes in several flavors:

Field-by-field quality assurance using
internal checks within a given run: single-run QA

Since DR4, we make available the single-run and summary QA outputs;
since overlap QA may involve data which are not public yet,
we do not publish those outputs, but may do so in the future. These
pages are devoted to a detailed description of single-run QA and a
description of overall assessments of SDSS data quality.